why new signals on old line?

[big daydreamer]

gregc

Are optical signals only necessary on passenger lines?

no, not at all

Google's driverless car technology replaces the driver, not the road.  The car still has to look for and read traffic lights. http://youtu.be/YXylqtEQ0tk?t=6m36s

 

[gregc]

nbrodar

PTC is horribly expensive, and still currently untried.  PTC requires a massive infrastructure both in lineside transponders and communications equipment, backroom computing power, and modifications to locomotives.

you gotta start somewhere.   If this is where rail transportation expects to be in a decade or two, at least in heavy traffic areas, why continue to invest in older technology it will replace?

nbrodar

There are traffic lights on roads for a reason. Imagine you are driving your car with only your GPS telling when to stop and go - that's the grade school explanation of PTC.

not gps, fully autonomous ... google driveless cars

 

[nbrodar]

PTC is horribly expensive, and still currently untried.  PTC requires a massive infrastructure both in lineside transponders and communications equipment, backroom computing power, and modifications to locomotives.  Optical signals while not cheap, are a proven technology and require no modifications to the rolling equipment.  Also PTC doesn't really protect shoving movements.  The person on the point of the movement still needs to able to see and read the lineside signals.

There are traffic lights on roads for a reason. Imagine you are driving your car with only your GPS telling when to stop and go - that's the grade school explanation of PTC. 

[gregc]

It seems the PTC is a automatic and remotely operated system forcing a train to stop, or at least slow down, and is hardly surprising with the technology today.    Which seems to make adding optical signals even more puzzling.

Are optical signals only necessary on passenger lines?

[nbrodar]

Which says exactly what Dave said.

[BRAKIE]

dehusman

PTC doesn't require signals, it requires a whole lot of communications and "signal" infrastructure, but it doesn't require an ABS or CTC sytem.  PTC is only being installed on lines that handle pasenger trains or a significant amount o RSSM type hazmat.  Lines that do onot meet that requirement will not have PTC.  PTC by itself doesn't increase capacity or train speeds, all it does is provide a layer of protection to stop a train that doesn't comply with a speed restriction or restrictive signal prior to it exceeding its authority.

 

Dave,For basic knowledge.

http://www.fra.dot.gov/Page/P0358

[dehusman]

PTC doesn't require signals, it requires a whole lot of communications and "signal" infrastructure, but it doesn't require an ABS or CTC sytem.  PTC is only being installed on lines that handle pasenger trains or a significant amount o RSSM type hazmat.  Lines that do onot meet that requirement will not have PTC.  PTC by itself doesn't increase capacity or train speeds, all it does is provide a layer of protection to stop a train that doesn't comply with a speed restriction or restrictive signal prior to it exceeding its authority.

[BRAKIE]

PTC is a mandate from the FRA plus the continuing growth of rail shipments means the once low traffic track is being upgraded to handle more trains or the track is a faster shorter route.

[nbrodar]

gregc

this morning i noticed a new signal bridge on I believe the old Lehigh Valley line in Manville, NJ heading west toward Phillipsburg.  They've done without signals on this line for probably close a century.   Why would they need to add light signals in this day of radios and other forms of communication?

 

Are you sure the line was non-signalled?  There has been a lot of work done up there, with tracks being realigned and signals moved.  Also adding signals to non-signalled track significately increases track capacity.

[wp8thsub]

There could be several reasons.  Maybe this line is being upgraded to comply with the positive train control rules http://en.wikipedia.org/wiki/Positive_train_control and signals are only part of the infrastructure improvements.

Even without PTC, radio communication isn't much of a safeguard.  Unsignalled trackage isn't necessarilly safer with radios than with phones or telegraph.

Signals wired on the Absolute Permissive Block principle provide a significant overlay of safety on a line otherwise dispatched using track warrants (or before that train orders and timetables).  Signals by themselves in such territory do not confer authority, existing solely to relay information about block occupancy.

If a line is slated for increased capacity, signaling allows for more trains to be operated with closer spacing, even without CTC.  Adding CTC (where the dispatcher remotely operates turnouts and signals at control points, and under which signals at such control points do confer authority instead of just occupancy) allows for greater capacity still.

See if this discussion addresses the line in question http://www.railroad.net/forums/viewtopic.php?f=127&t=94224&sid=fc2c4770cf3060f8c380dfc5a397a84c .

[mlehman]

Are they adding commuter rail, maybe?

[gregc]

this morning i noticed a new signal bridge on I believe the old Lehigh Valley line in Manville, NJ heading west toward Phillipsburg.  They've done without signals on this line for probably close a century.   Why would they need to add light signals in this day of radios and other forms of communication?